Switching apparatus



sept- 1940' c. E. LOMAX ET AL 2,214,907

SWITCHING APPARATUS Filed Dec. 30, 1938 2 Sheets-Sheet l Fig-l 36 lnsulaf/on 32 lnsulafion INVENTORS Clarence E. Lmmax and BY Benz-5a T. PIar'firi ATTORNEYS Sept. 17, 1940. c. E. LOMAX El AL 2,214,907

SWITCHING APPARATUS Filed Dec. 50, 1938 2 Sheets-Sheet 2 o O o 53 c o lnsu/aiion 74 52 59 I 64 U I] I i 5 63 /3 #69: [nsu/alion x g; x II a. lnsu/a zon v 65%? /0-\ v n xnsulalmn INVENTORS Elar'encs ELmmax and BY Bangs I War'fin ATTORNEYS Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE SWITCHING APPARATUS Clarence E. Lomax, Oak Park. and George T. Martin, Chicago, Ill., assignors to Associated Electric Laboratories, Inc Chicago, 11]., a cor- Wration of Delaware The present invention relates to switching apparatus and more particularly to improvements in switching apparatus suitable for use in automatic telephone exchanges.

In a telephone system one oi the major items cost, in regard to the construction and installation of any automatic telephone exchange, is that of connecting the large number of groups 01' lines to the many switches and the construction of the multiples between the switches. Usually this construction work is done manually, the conductors in a particular portion of the multiple and the conductors in a particular group of the lines being soldered to the respective terminals of a corresponding group of the switches. This item 01' cost may be materially reduced by minimizing the number of terminals included in each switch provided the number 0! groups of lines and the number of lines in each group to l which the switch has access is not reduced rendering it necessary to employ a larger number of switches in the system.

It is an object of the present invention to provide improved switching apparatus having access to a predetermined number of groups of lines, each group of lines including a predetermined number of lines, which switching apparatus is so constructed and arranged that a minimum number of terminals are required therein in order to terminate the respective lines in the respective groups 01 lines.

Another object of the invention is to provide improved switching apparatus having access to a number of groups of lines and selectively oper- 35 ative to connect together selectively corresponding lines in two of the groups oi lines, and to connect together simultaneously corresponding lines in each of the number of groups of lines.

In the improved switching apparatus there M may be incorporated diflerent forms of switching unit, two forms being illustrated and described in detail hereinafter. In each form 01 the switching unit there are provided a set of stationary contacts arranged in a longitudinally extending 45 row and first and second sets oi. movable contacts arranged in two longitudinally extending and substantially parallel rows disposed on opposite sides oi' the set of stationary contacts. More particularly, the set of stationary contacts com- 510 prises a number of individual stationary contacts,

each being of substantially T-shape and having a stem portion and a head portion providing two wiper portions; and each of the sets 01' movable conductors comprises a number 01' individual conductors, each having a flexible shank porof stationary contacts.

tion and a contact portion. The contact portions of corresponding conductors in each of the sets oi conductors are arranged in spaced relation with the respective wiper portions of corresponding stationary contacts in the set of stationary contacts. Also, there is provided a longitudinally extending insulating plate for mounting the stems of the stationary contacts in the set oi stationary contacts at points remote from the head portions thereof and for mounting the shank portions of the conductors in each of the sets of conductors at points remote from the contact portions thereof. Furthermore, two insulating bars are individually associated with the respective conductors in the respective sets of conductors and motor means comprising two electromagnetic devices individually associated with the insulating bars are provided which are selectively operative to move selectively and simultaneously the insulating bars in a lateral direction. When the insulating bar individually associated with the first set of conductors is moved laterally, the shank portions of the conductors in this set of conductors are flexed laterally, thereby to cause the contact portions thereof to engage the associated wiper portions of the respective stationary contacts in the set of stationary contacts; and when the insulating bar individually associated with the second set 01 conductors is moved latterally, the shank portions of the conductors in this set of conductors are flexed laterally, thereby to cause the corresponding contact portions thereof to engage the associated wiper portions of the respective stationary contacts in the set Also, a circuit network is provided for the purpose of selectively controlling the energization of the electromagnetic devices in the motor means.

The respective stationary contacts in the set of stationary contacts are adapted to terminate the respective conductors 01' a first group 01' lines; the respective conductors in the first set of conductors are adapted to terminate the respective conductors of a second group of lines; and the respective conductors in the second set of con- 5 ductors are adapted to terminate the respective conductors of a third group of lines. By selectively controlling the energization oi the two electromagnetic devices, the respective lines in the second and third groups 01' lines may be se-' lectlvely connected to the respective lines in the first group oi lines; and by controlling the energization oi the two electromagnetic devices to obtain simultaneous energization thereof, the respective lines in both the second and third groups of lines may be simultaneously connected to the respective lines in the first group of lines. Accordingly, the improved switching apparatus utilizing the switching unit described has the 'eflective switching capacity of conventional switching apparatus utilizing two separate and distinct switching units of conventional construction; yet, the switching unit described includes a number of terminals only fitty per cent greater than the number 01' terminals included in one conventional switching unit. Hence. the improved switching apparatus eflects a net saving in the number of terminals required in the switches of the telephone system of twenty-five per cent, thereby reducing the number of soldered connections required in the system by a like amount.

In the first form 0! the switching unit, the electromagnetic devices individually associated with the insulating bars are arranged closely adjacent the respective sets of conductors and disposed on opposite sides or the switching unit; and in the second form of the switching unit, side members are provided which partially enclose the sets of conductors and respectively carry the electromagnetic devices on the outer walls thereof on opposite sides of the switching unit.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figure l is a perspective view of a switching unit constructed and arranged in accordance with the present invention; Fig. 2 is a diagrammatic illustration of a circuit arrangement for controlling the energlzation of the electromagnetic devices included in the switching unit shown in Fig. 1; and Fig. 3 is a perspective view of a modified form of the switching unit.

Referring now to Fig. 1 of the drawings, the switching unit there shown comprises a rectangular supporting plate I0 formed of insulating material, such as Bakelite, carrying a centrally disposed and longitudinally extending row of upstanding wiper sets II, constituting a set of stationary contacts, and two longitudinally extending rows of upstanding conductors I2 and I3 respectively arranged on opposite sides of the set of wiper sets II and constituting first and second sets of movable conductors. Each of the wiper sets II comprises complementary and substantially T-shaped wipers Na and Ill) formed of flexible conducting material and arranged in engaging side-by-side relationship, the heads of the wipers being disposed in spaced relationship with respect to the supporting plate III, and the stems of the wipers being embedded in the supporting plate II) and extending therethrough to provide a terminal on the outer ends of the stems of the wipers Ila and III) comprising the wiper sets II. These terminals provided on the wiper sets II, comprising the set of stationary contacts, are adapted to terminate the respective conductors of a group of lines. Also, the outer ends of the heads of the Wipers I la and I II) of each wiper set II are flared outwardly in opposite directions in order to provide guiding grooves disposed therebetween adjacent the opposite ends of the head of the wiper set, which guiding grooves are adapted to receive adjacent contact portions of two of the conductors I2 and I3 disposed in the respective sets of movable conductors, in a manner more iully described subsequently. Each of the conductors I2 and I3 comprises a relatively long section of flexible round stock, a contact portion of each conductor adjacent the outer end thereof being arranged in alignment with respect to an adjacent one 01' the guiding grooves provided in the head of one of the wiper sets I I and the shank of the conductor being embedded in the supporting plate I0 and extending therethrough to provide a terminal on the outer end thereof. These terminals provided on the conductors I2, comprising the first set of movable conductors, and on the conductors I3, comprising the second set of movable conductors, are adapted to terminate the respective conductors of two respective groups of lines. Preferably, the shanks of the conductors I2 and I3 and the stems of the wipers I la and I II) comprising the wiper sets II are molded directly in the supporting plate I0.

The head of every other one of the wiper sets I I is of the same length, while the heads of adjacent ones of the wiper sets II are of different lengths so that the guiding grooves provided in the heads of the wiper sets are arranged in two longitudinally extending rows, adjacent guiding grooves in each of the rows being staggered laterally therealong, thereby to accommodate separating movements between the complementary wipers of each wiper set without any interference with adjacent wiper sets. Similarly, adjacent ones of the conductors I2 in the first set of movable conductors are staggered laterally along the longitudinally extending row; and adjacent ones of the conductors I3 in the second set of movable conductors are staggered laterally along the longitudinally extending row.

From the foregoing description of the construction and arrangement of the longitudinally extending set of wiper sets II and the longitudinally extending sets of conductors I2 and I3, it will be understood that a contact portion of each of the conductors adjacent the outer end thereof is arranged adjacent and disposed a fixed distance from a corresponding one of the guiding grooves provided in the head of a corresponding one of the wiper sets.

Two flanged supporting members I4 and I5, respectively, are securely fastened to the opposite sides of the supporting plate In by a number of screws I6. The supporting member It carries an electromagnetic device I8 suitably secured thereto; and the supporting member I carries an electromagnetic device I9 suitably secured thereto. The electromagnetic device I8 comprises a magnetic core provided with pole pieces 2| and 22, a movable armature 23 pivotally supported by a pivot pin 24 upon the pole piece 22 and an electromagnetic coil 25 associated with the core 20. Similarly, the electromagnetic device I9 comprises a magnetic core 26 provided with pole pieces 21 and 28, a movable armature 29 pivotally supported by a pivot pin 30 upon the pole piece 28 and an electromagnetic coil 3i associated with the core 26. The upper end of the armature 23 is provided with two oppositely and longitudinally extending arms 32 and 33, respectively, having inwardly turned portions 34 and 35, respectively. Similarly, the upper end of the armature 29 is provided with two oppositely and longitudinally extending arms 36 and 31, respectively, having inwardly turned portions 38 and 39, respectively.

Also, the shanks of the longitudinally extending row of conductors I2 are embedded in a longitudinally extending insulating bar 40 adjacent the outer ends thereof; and the shanks of the longitudinally extending row of conductors II are embedded in a longitudinally extending insulating bar 4! adjacent the outer ends thereof. Preferably, the bars 44 and 4| are formed of moldable insulating material, such as "Bakelite," and the shanks of the conductors l2 and it, respectively, are molded directly therein. The bar 40 is securely retained between the inwardly turned portions 34 and 55 of the arms 42 and II, respectively, by two screws 42 extending through openings provided in the inwardly turned portions 54 and and threaded into tapped holes provided in the opposite ends of the bar 45. Similarly, the bar 4i is securely retained between the inwardly turned portions 35 and 35 of the arms 56 and 31, respectively, by two screws 43 extending through openings provided in the inwardly turned portions 35 and II andthreaded into tapped holes provided in the opposite ends of the bar 4i.

From the foregoing description of the construction and arrangement of the switching unit, it will be understood that the portions of the shanks of the conductor; I2 and i3 adjacent the inner ends thereof are securely anchored in the supporting plate It and that the portions of the shanks of the conductors I2 and I3 adjacent the outer ends thereof are securely anchored in the bars and 4!, respectively, while the portions of the stems oi the wiper set ii adjacent the inner ends thereof are securely anchored in the supporting plate I 6. The outer ends of the flexible conductors l2 are flexible as a unit with the bar 40 to move the contact portions thereof into engagement with the respective guiding grooves provided in the heads 0! the respective wiper sets H; and the outer ends of the flexible conductor ii are flexible as a unit with the bar 4| to move the contact portions thereof into engagement with the respective guiding grooves provided in the heads of the respective wiper sets Ii. Accordingly, the row of wiper sets Ii constitute a set of stationary contacts, while the rows of conductors l2 and II constitute sets of movable contacts adapted to be moved into engagement therewith.

In the operation of the switching unit the sets of conductors i2 and I! are adapted to be selectively and independently moved into engagements with the associated sets of wiper sets Ii, the set of conductors i2 being moved into engagements with the associated set of wiper sets I i when the winding 25 of the electromagnetic device [8 is energized, and the set of conductors I! being moved into engagement with the associated set of wiper sets I I when the winding ii of the electromagnetic device I! is energized. More particularly, when the winding 25 of the electromagnetic device i8 is energized, the armature 23 is rotated about the pivot pin 24 in a counterclockwise direction in order to cause the bar 40 carried thereby and the set of conductors l2 embedded in the :bar to be moved laterally toward and into engagement with the associated set of wiper sets" Ii. Similarly, when the winding 31 of the electromagnetic device I! is energized, the armature 28 i rotated about the pivot pin 35 in a clockwise direction in order to cause the bar 4| carried thereby and the set of conductors i3 embedded in the bar 4| to be moved laterally toward and into engagement with the associated set of wiper sets H. Thus, it will be apparent that by energizing selectively the windings 25 and ii of the electromagnetic devices l4 and I5, respectively, the groups of lines terminated by the sets of conductors i2 and II, respectively, may be selectively connected to the group of lines terminated by the set of wiper sets Ii; and by energizing simultaneously the windings 25 and II of the electromagnetic devices I. and II, respectively, the groups of lines terminated by the sets of conductor l2 and i3, respectively, may be simultaneously connected to the group of lines terminated by the set of wiper ests ii.

In Fig. 2 of the drawings a circuit arrangement for controlling the energization of the windings 25 and II of the electromagnetic devices it and I9, respectively, included in the switching unit of Fig. 1, is diagrammatically illustrated. This circuit arrangement comprises a multiposition switch 45 of the rotatable type including two contact banks 46 and 41 and a wiper 48 of the double-ended type, the ends of the wiper 48 engaging corresponding contacts in the contact banks 46 and 41, respectively, during operation of the switch 45. The switch 45 may be either of the automatic or manually operable types as desired; and the wiper 45 is rotatable in a counterclockwise direction irom a normal position in which the first contacts in the respective contact banks 46 and 41 are engaged thereby. A circuit network is provided which includes the windings 25 and 3i of the electromagnetic devices i8 and i9, respectively, and the wiper 48 and the contests in the contact banks 46 and 41 o! the switch 45. The circuit network is so connected and arranged that both of the windings 25 and II are deenergized when the wiper 46 engages the first contacts in the respective contact banks 46 and 41; the winding 25 is energized when the wiper 48 engages the second contacts in the respective contact banks 46 and 41; the winding II is energized when the wiper 48 engage the third contacts in the respective contact banks 46 and 41; and both of the windings 25 and H are energized when the wiper 48 engages the fourth contacts in the respective contact banks 46 and 41. The energizing circuits mentioned above are obvious and have not been specifically traced in the interest oi? brevity.

In Fig. 3 of the drawings a modified form of the switching unit is shown which comprises an insulating supporting plate i6 carrying a set of wiper sets ii and two sets of conductors l2 and I 3 which are constructed and arranged in a manner precisely the same as that previously described in connection with the preferred embodiment oi the switching unit shown in Fig. 1. Also, this embodiment of the switching unit comprises two insulating bars 40 and 4i in which the shanks of the conductors I 2 and I3, respectively, are embedded in the previously described manner; and a. unitary supporting member 50 of substantially inverted U-shape configuration is secured to the supporting plate Ill by a number of screws 5|. Furthermore, the supporting member 50 is provided with a cut-out portion adjacent the top end thereof in order to provide two upstanding side walls 52 and 53 arranged in spaced relationship with respect to each other and secured together adjacent the ends thereof by two straps 54. The side walls 52 and 53 of the supporting member 50 enclose the sides of the sets of conductors l2 and i3 disposed on opposite sides of the set of wiper sets H, the ends of the sets of conductors i2 and i3 and the heads of the wipers comprising the set of wiper sets I i being arranged in alignment with the cut-out portion provided in the supporting member 50. The side wall 52 is provided with an outwardly extending arm 55 to which an electromagnetic device 56 is secured by a screw 51; and the side wall 53 is provided with an outwardly extending arm 58 to which an electromagnetic device 28 is secured by a screw 60, the electromagnetic devices 56 and 59 being arranged on opposite sides of the supporting member 50 in substantial alignment with eac other.

The electromagnetic device 56 comprises a core, a. movable armature SI extending through an elongated slot 62 provided in the side wall 52 and an electromagnetic winding 63; and the elec tromagnetic device 59 comprises a core, a movable armature, not shown, extending through an elongated slot, not shown, provided in the side wall 53 and an electromagnetic winding 54. A connecting element 65 provided with a downwardly extending body portion 66 having an outwardly turned arm 67 secured to the movable armature Si is associated with the electromagnetic device 55. Also, the connecting element 55 is provided with two outwardly extending arms 88 and 69 having inwardly turned portions l and ll, respectively, between which inwardly turned portions ill and "H the bar 50 is secured by two screws 12 extending through openings provided in the inwardly turned portions l0 and ll and threaded into tapped holes provided in the opposite end of the bar 40. A connecting element 13 of a construction similar to the connecting element 65 is associated with the electromagnetic device 59, the connecting element 73 being secured to the movable armature of the electromagnetic device 59 and provided with two outwardly extending arms 74 and 15 having inwardly turned portions 16 and 11, respectively, between which the insulating bar H is secured by two screws 18 extending through openings provided in the inwardly turned portions 16 and ll and threaded into tapped holes provided in the opposite ends of the bar 4!. Preferably, the connecting elements 55 and 73 are formed of a non-magnetic material such as brass in order to prevent these elements from carrying magnetic flux and tending to stick to the adjacent portions of the side walls 52 and 53, respectively. The elongated slot 62 formed in the side wall 52 constitutes a fulcrum edge for the movable armature SI of the electromagnetic device 55 due to the fact that the upper end of the connecting element 65 is positioned by the bar 40. Similarly, the elongated slot, not shown, formed in the side wall 53 constitutes a fulcrum edge for the movable armature of the electromagnetic device 59 due to the fact that the upper end of the connecting element 13 is positioned by the bar 4 I.

From the foregoing description of the construction and arrangement of this embodiment of the switching unit, it will be understood that the sets of conductors l2 and [3 may be selectively and independently moved into engagement with the associated set of wiper sets H by selectively energizing the windings 63 and 54 of the electromagnetic devices 55 and 59, respectively. More particularly, when the winding 63 of the electromagnetic device 56 is energized, the movable arrnature 6! thereof is pivoted in a counterclockwise direction, thereby to cause the connectlug-element 65 to move the bar 40 and the set of conductors l2 embedded therein laterally into engagement with the associated set of wiper sets H. Similarly, when the winding 54 of the electromagnetic device 59 is energized, the movable armature thereof is pivoted in a clockwise direction, thereby to cause the connecting element '13 to move the bar II and the set of conductors l3 embedded therein laterally into engagement with the associated set of wiper sets I l. Accordingly, the group of lines terminated by the sets of conductors l2 and I3, respectively, may be selectively and simultaneously connected to the group of lines terminated by the set of wiper sets ll.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. Switching apparatus comprising, in combination, a stationary contact provided with a wiper portion, first and second conductors each having a resilient shank portion and a. contact portion associated in spaced relation with the wiper portion of said stationary contact, means including an insulating support for fixedly mounting said stationary contact at a point remote from the wiper portion thereof and for fixedly mounting the shank portions of said first and second conductors at points remote from the respective contact portions thereof, means including a first electromagnetic device carried by said support for flexing the shank portion of said first conductor to move the contact portion there of into engagement with the wiper portion of said stationary contact, and means including a second electromagnetic device carried by said support for fiexing the shank portion of said second conductor to move the contact portion thereof into engagement with the wiper portion of said stationary contact.

2. Switching apparatus comprising, in combination, a set of stationary contacts, each of said stationary contacts having a wiper portion, first and second sets of conductors, each of said conductors having a resilient shank portion and a contact portion, the contact portion of a corresponding conductor in each of said first and second sets of conductors being associated in spaced relation with the wiper portion of a cor responding stationary contact in said set of stationary contacts, means including an insulating support for fixedly mounting the stationary contacts in said set of stationary contacts at points remote from the wiper portions thereof and for fixedly mounting the shank portions of the conductors in each of said first and second sets of conductors at points remote from the respective contact portions thereof, means including a first electromagnetic device carried by said support and associated with said first set of conductors for simultaneously flexing the shank portions of the conductors therein to move the contact portions thereof into engagement with the wiper portions of the corresponding stationary contacts in said set of stationary contacts, and means including a second electromagnetic device carried by said support and associated with said second set of conductors for simultaneously flexing the shank portions of the conductors therein to move the contact portions thereof into engagement with the ,wiper portions of the corresponding stationary contacts in said set of stationary contacts.

3. Switching apparatus comprising, in combination, a longitudinally tionary contacts, each'of said stationary tacts having a wiper portion, first and longitudinally disposed sets of conductors ar-v ranged on opposite sides of said longitudinally disposed set of stationary contacts, each said conductors having a resilient shank portion and a contact portion, the contact portion of a corresponding conductor in each of said first and second sets of conductors being associated in 20 mote from the respective contact portions thereof, means including a first electromagnetic device carried by said insulating plate and asso-.

ciated with said first set of conductors for simultaneously flexing laterally the shank portions of the conductors therein to move the contact portions thereof into engagement with the wiper portions of the corresponding stationary contacts in said set of stationary contacts, and means including a second electromagnetic device carried by said insulating plate and associated with said second set of conductors for simuletaneously flexing laterally the shank portions of the conductors therein to move the contact portionsthereof into engagement with the wiper portions of the corresponding stationary contacts in said set of stationary contacts.

4. Switching apparatus comprising, in combination, a set of stationary contacts, each of said stationary contacts having a wiper portion,- first and second sets of conductors, each of said conductors having a resilient shank portion and a contact portion, the contact portion of a corresponding conductor in each of said first and second sets of conductors being associated in spaced relation with the wiper portion of a corresponding stationary contact in said set of stationary contacts, means including an insulating support for fixedly mounting the stationary contacts in said set of stationary contacts at points remote from the wiper portions thereof and for fixedly mounting the shank portions of the conductors in each of said first and second sets of conductors at points remote from the respective contact portions thereof, a first bar associated with the conductors in said first set of conductors adjacent the contact portions thereof, a second bar associated with the conductors in said second set of conductors adjacent the contact portions thereof, means including a first electromagnetic device carried by said support formoving said first bar to flex simultaneously the shank portions of the conductors in said first set of conductors, thereby to move the contact portions thereof into engagement with the wiper portions of the corresponding stationary contacts in said set of stationary contacts, and means including a second electromagnetic device carried by said support for moving said second bar to flex simultaneously the shank portions of the conductors in said second set of conductors, thereby to move the contact portions thereof into engagement with the wiper portions of the corresponding stationary contacts in said' set of stationary contacts.

5. Switching apparatus comprising, in combicontact 1mm; 3 mti'ally :T-sh'apa'd-configuration and including a stem portion and a headportion providing two wiper first and second conductors arranged on opposite sides of said stationary con- "tact,ejach of said conductors having a resilient shank portion and a contact portion, the contactportions 0! said first and second conductors being associated in spaced relation with the respective wiper portions of said stationary contact, means for fixedly mounting the stem portion of said stationary contact at a point remote from the head portion thereof and for fixedly mounting the shank portions of said first and second conductors at points remote from the the associated wiper portion of said stationary contact.

6. Switching apparatus comprising, in combination, a longitudinally disposed set of stationary contacts, each of said stationary contacts having a substantially T-shaped configuration and including a stem portion and a head portion providing two wiper portions, first and second longitudinally disposed sets of conductors arranged on opposite sides of said longitudinally disposed set of stationary contacts, each of said conductors having a resilient shank portion and a contact portion, the contact portion of a corresponding conductor in each of said first and second sets of conductors being associated in spaced relation with the respective wiper pertions of a corresponding stationary contact in said set oi. stationary contacts, means including a longitudinally disposed insulating plate for fixedly mounting the stem portions of the stationary contacts in said set of stationary contacts at points remote from the respective head portions thereof and for fixedly mounting the shank portions of the conductors in said first and second sets of conductors at points remote from the respective contact portions thereof, means associated with said first set of conductors for simultaneously flexing laterally the shank portions of the conductors therein to move the contact portions thereof into engagement with the associated wiper portions of the corresponding stationary contacts in said set of stationary contacts, and means associated with said second set of conductors for simultaneously flexing lat- .erally the shank portions of the conductors therein to move the contact portions thereof into engagement with-the associated wiper portions oi! the corresponding stationary contacts in said set of stationary contacts.

'7. Switching apparatus comprising, in combination, a longitudinally disposed set of stationary contacts, each of said stationary contacts having a substantiallyT-shaped configuration and including a stem portion and a head portion providing two wiper portions, first and second longitudinally disposed sets of conductors arranged on opposite sides of said longitudinally disposed set of stationary contacts, each of said conductors having a resilient shank portion and a contact portion, the contact portion of a corresponding conductor in each of said first and second sets oi conductors being associated in spaced relation with the respective wiper portions of a corresponding stationary contact in said set of stationary contacts, means including a longitudinally disposed insulating plate for fixedly mounting the stem portions of the stationary contacts in said set of stationary contacts at points remote from the respective head portions thereof and for fixedly mounting the shank portions of the conductors in said first and second sets of conductors at points remote from the respective contact portions thereof, a first bar associated with the conductors in said first set of conductors adjacent the contact portions there- 01, a second bar associated with the conductors in said second set of conductors adjacent the contact, portions thereof, means including a first electromagnetic device for moving said first bar to flex simultaneously and laterally the shank portions of the conductors in said first set 0! conductors. thereby to move the contact portions thereof into engagement with the associated wiper portions of the corresponding stationary contacts in said set 0! stationary contacts, and means including a second electromagnetic device or moving said second bar to flex simultaneously and laterally the shank portions 01' the conductors in said second set of conductors, thereby to move the contact portions thereof into engagement with the associated wiper portions of the corresponding stationary contacts in said set of stationary contacts.

CLARENCE E. LOMAX.

GEORGE T. MARTIN. 

